Email Blocking?

If a certain company wanted to block me from sending them emails, could they and would I know about it...

I'm trying to reply to an email from a company but replying to a known working address and also the address I sent the originating email now gets me an email from my Mail Delivery System claiming the following....

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

***@***.co.uk
host mailrelay02.***.co.uk [***.***.***.***]
SMTP error from remote mail server after initial connection:
554 mailrelay02.***.co.uk

Any ideas.

Yes, they could block you and you wouldn't necessarily know that they had.

Emails that are sent to a server can be rejected, in which case you get a message like the one you've had, or they can be discarded. If it's the latter, you get no notification of a failure and they don't receive the email.

It could be a misconfiguration. Does the email address you are sending from use an outgoing mail server that should be handling email from that domain? If you aren't using an email domain linked to your ISP but are using the ISP's mail server to send through, you may get a rejection from some third party recipient servers.

Edited by caffn8me (Wed 26-Jul-17 01:02:45)

You could try creating a temporary account on gmail, Outlook, etc and try sending to the address using that - would potentially indicate if they were specifically blocking your email address or whether they have a wider issue.

In reply to a post by mlmclaren:

If a certain company wanted to block me from sending them emails, could they and would I know about it...

From a technical POV it's easy. I run my own mail server and all I have to do is create a rule that sends a matching email to the bit bucket. The sending server will have no idea that it's been blacklisted.

In fact I used to do that. I operate a DEA (Disposable Email Address) system to cut out spam so I have a slowly growing list of incoming addresses that I don't accept. Originally I told my server to silently accept them but then I realised that was wasting my bandwidth since it had to download the rubbish and it confirmed that the address was valid. So now the server rejects the email address immediately.

But yeah - silent blackholing is easy if you have enough access to configure the mail server.

Edited by Andrue (Wed 26-Jul-17 08:54:16)

SMTP 554 is 'rejection from the Recipient Domain'.

https://support.symantec.com/en_US/article.TECH16984...

So it could be that your server has been blacklisted or (less likely) that your email server is not authorised to send emails on your behalf.

Edited by Andrue (Wed 26-Jul-17 09:05:05)